A method is known in which edited image data or image data obtained by optical scanning is separated into character and photographic portions and these portions are subjected to image processing individually.
In the technique described in Patent Literature (PTL) 1, continuous tone data and bi-level data are individually encoded by a computer, and transferred to and decoded by an inkjet printer. In the printer, the continuous tone data is halftoned to bi-level color data. The bi-level data and the bi-level color data are combined to form print data, which is then printed.